Engraving machine

ABSTRACT

A laser engraving machine with a three-point suspension system and an inverted X-Y axis support system wherein the X-axis beam is to and mounted below the Y-axis beams and the Y-axis beams are mounted inwardly of the outer ends of the X-axis beam and are structurally integrated with the machine housing. In addition, a counterweight in the form of a second, independently activatable laser is added to the drive belt to reduce or eliminate vibration during rapid reciprocal movement of the tool during an engraving process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 16/987,529, filed Aug. 7, 2020 which claims priority to U.S.Provisional Patent Application Ser. No. 62/986,056, filed on Mar. 6,2020, the entire disclosures of which are incorporated by reference.

FIELD OF THE INVENTION

This document describes an improved laser engraving machine forengraving objects made of various materials including stone, metal woodand plastic with letters, numbers, images and combinations thereof, andmore particularly to an engraving machine having a novel arrangement ofX and Y axis tool support and guidance structures to provide improvedstructural strength, thereby allowing for the use of lighter materialsof construction. The disclosure further describes a device having acounter-weighted X-axis laser drive, which substantially eliminatesvibration and loss of image resolution in the engraving process.

BACKGROUND OF THE INVENTION

Engraving machines, particularly those using lasers to implement theengraving process, typically comprise a cabinet that can be mounted on atable or the like over an object such as a grave marker to be engraved.Within the cabinet there are X and Y axis support beams for a steppermotor drive system to move the laser tool incrementally and under thecontrol of a digital program through a two-dimensional field over theobject surface to be engraved at a fixed focal distance. The X-axis beamdirectly supports the laser for movement in the X direction while theY-axis beams extend under and provide support to the X-axis beam forincremental translation or movement in the Y-axis direction.

As shown in FIG. 1, the prior art approach necessarily locates theY-axis beams 14 and 16 supporting the X-axis beam 12 under the X axisbeam and as far apart as possible to give the laser tool 10 maximumtranslation capability. The Y-axis beams 14 and 16 are tied at theiropposite ends into the front and rear side panels of the cabinet and addlittle rigidity to the cabinet structure. See, for example, my patentno. 10,654,127. Because the beams 14 and 16 are so far apart, the lasercabinet must be made of a heavier gauge, high tensile strength metal,such as steel, in order to have adequate rigidity to preserve resolutionin the engraving process and not allow any flexing or vibration in thehousing during the very rapid back and forth movement of the laser tool.

SUMMARY OF THE INVENTION

In accordance with the present disclosure, the first improvementdescribed involves an inversion of the X and Y stepper motor tracksupport beams so that the X-axis support beam is mounted under theY-axis support beams. This allows the Y-axis support beams to be broughtcloser together adding rigidity to the frame of the laser housing andreducing or eliminating the use of steel in the construction of thelaser housing in favor of the use of a more lightweight material such asaluminum.

A second aspect of the disclosure provided herein involves thereorientation of the continuous loop belt which is used to incrementallytranslate the laser tool along the X-axis so that the axes of rotationof the end wise pulleys are vertical rather than horizontal. Inaddition, a counterweight is added on the side of the belt opposite theengraving tool. The counterweight, therefore, moves in the oppositedirection of the laser during incremental reciprocal movement, givingrise to a conservation of momentum, which dramatically reduces vibrationand improves laser engraving accuracy and image resolution in theengraving process.

As further described hereinafter, the counterweight, best constructed tosubstantially, if not identically, equal the mass of the laser tool, canbe a second laser which is independently activated to carry out anadditional portion of the engraving process simultaneously with theforward mounted laser. This of course adds complexity to the programmingprocess but that technology is within the skill in the art. It will alsobe noted that the device shown in FIG. 3 of the drawings hereinafterdescribed corresponds substantively with the three-point laser supportand guidance system disclosed in my U.S. Pat. No. 10,654,127, the entiredisclosure of which is incorporated herein by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is diagrammatic view of the prior art X and Y beam supportstructure;

FIG. 2 is diagrammatic view of the new X and Y beam laser supportstructure;

FIG. 3 is a perspective view of a laser machine including a lasercabinet having X and Y engraving tool translation capability and a pairof lasers 10 and 13 mounted for movement in opposite directions onopposite sides of a grooved stepper motor drive belt; and

FIG. 4 is a bottom view of the apparatus of FIG. 3 showing the use oftwo laser in a counterweighted fashion on opposite sides of the X-axisincremental drive belt 42.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT

Reviewing, the prior art X and Y beam structure diagrammatically shownin FIG. 1, it should be noted that the X-axis support beam 12 is mountedover the widely spaced Y-axis support beams 12 and 14 to allow the lasertool 10 to realize maximum translation scope in the positive andnegative X-axis direction.

FIG. 2 on the other hand, shows the new arrangement in which the lasertool 10 and the X-axis support structure 18 is mounted to and below theY-axis support beams 20 and 22 thereby allowing those beam structures tobe moved closer together, adding substantial additional rigidity to thehousing 24 shown in FIGS. 3 and 4.

Referring to FIGS. 3 and 4, the laser machine 24 is shown to comprise abox-like metal housing with an interior volume adapted to contain theX-axis support structure 18 for the downwardly-aimed laser engravingtool 10 which is moveable along the X-axis by means of a belt 42 mountedon pulleys 44 and 46 driven by a stepper motor 43 as disclosed in myprior patent documents as described above. Y-axis drive is provided by asecond stepper motor 45. The housing sits, in this example, on the topsurface of a table 36, which is mounted over an elevator table 38 onwhich the object 40 is to be engraved rests. The elevator table allowsthe object 40 to be put in place and then raised up into the focal rangeof the laser tool 10.

However, additional adjustment for both laser focus and theaccommodation of any non-level condition in the surface of the object 40to be engraved, is provided by means of the three-point tool support andguidance system incorporating screw shafts 26, 28 and 30 arranged in atriangular pattern and adjustable in this case by hand to allow levelingof the laser tool translation field so that it parallels the surface ofthe object 10 to be engraved. Again, this is fully described in my priorart patent.

In accordance with the invention, and the novel subject matter describedherein, the Y-axis beams 20 and 22, which extend between and are affixedto the front and rear panels of the housing 24 are mounted closertogether without having a negative effect on X-axis translation scope.The Y-axis beams are structurally tied into the front and rear-housingpanels adding substantial rigidity to the housing and, as describedabove, allowing for the use of lighter, less expensive materials ofconstruction.

The cabinet or housing 24 has a hinged lid 32 with an exhaust port 34connected to an exhaust system (not shown) to evacuate dust and debrisas well as smoke from the area where the laser tool 10 is operating.Similar machinery is used where the engraving tool 10 takes the form ofa mechanical device such a diamond tip rotary tool. Maximum structuralrigidity is provided by locating the Y axis beams 20 and 22 at theone-third and two-thirds distance points between the side panels 23 and25 of the housing. By way of example, for a housing or cabinet thatprovides a 48 inch field, the beam 20 is located at least approximately16 inches from the side panel 23 while beam 22 is 32 inches from theside panel 23 and 16 inches from beam 20.Variations of this spacing arealso advantageous and may be necessary to accommodate various factorssuch as cabinet design and the mounting locations of the variousinternal components.

As indicated above, another aspect of the innovative subject matterdescribed herein is the addition of a counterweight, here in the form ofa second laser tool 13 identical to laser tool 10, mounted on the belt42 directly opposite; i.e., on the other side of the belt 42 so that asthe laser engraving tool 10 moves from right to left during theincremental engraving process, the tool 13 moves from left to right andvice versa. The mass of the counterweight is chosen to be at leastsubstantially equal the mass of the tool and, as will be understood,moves in directions opposite to movement of the tool. This gives rise toa conservation of momentum, which damps out the tendency of a singlelaser engraving tool 10 to vibrate or flex the belt 42 during the rapidreciprocal incremental movement of the tool during a very fine, highresolution engraving process. The result is substantial improvement inthe resolution of the images and other figures to be engraved.

Looking further to FIG. 4, the laser source 50 is shown mounted towardthe back of the cabinet and the output is aimed at a mirror 52 whichredirects the beam to a second beam-splitter mirror 54 which in turndirects the beam to the laser tool 13. The beam also passes through themirror 54 to a second mirror 56 which directs the beam to the laser tool10. It will be understood that two lasers may be used with two sets ofmirrors to transmit their respective beams to the tools 10 and 13 sothat they may operate essentially independent of one another during anengraving process.

It is to be further understood that the invention has been describedwith reference to an embodiment which is deemed to be illustrative innature and that persons skilled in the art will see and understand thatvarious modifications and additions to the subject matter describedherein may be made.

What is claimed:
 1. An engraving machine X-axis drive system comprising:a closed loop drive belt with a stepper motor drive; said belt beingmounted on and extending between a pair of pulleys to define twoparallel spans of the belt that move in opposite directions; anengraving tool in the form of a first laser having a known mass attachedto one side span of the belt for movement therewith; and a counterweightcomprising a second laser of substantially the same mass as the firstlaser attached to a second side span of the belt for movement therewithin a direction opposite to that of the first laser.
 2. An engravingmachine X-axis drive system as defined in claim 1 wherein the pulleyshave parallel vertical axes or rotation.
 3. An engraving machine X-axisdrive system as defined in claim 1 further including means forindependently activating the first and second lasers during X-axis scansthereof.
 4. An engraving machine X-axis drive system as defined in claim2 wherein the first and second lasers are mounted so as to produce laserbeams extending along a vertical Z-axis.